Copper phthalocyanine pigments are known for their attractive blue color and outstanding fastness properties. The alpha and beta crystal modifications of copper phthalocyanine are particularly interesting as pigments. The preparation of pigmentary alpha and beta forms of copper phthalocyanine, for example by conditioning, is well-known in the art.
Small partide size copper phthalocyanine pigments having an average partide size below 0.1 .mu.m are especially interesting and used in large quantities on the worldwide pigment market due to their high color strength and high saturation.
Large particle size copper phthalocyanines are also known in the art, primarily in platelet crystal form. Large particle size, platelet-shaped copper phthalocyanine pigments are generally used as effect pigments. For example, U.S. Pat. No. 4,370,270 discloses a large particle size, platelet form of beta copper phthalocyanine which has a reflection maxima between 610 and 640 and between 710 and 740 nm and displays optical effects similar to-a metallic pigment. Although the coloristic properties of this pigment form are unique, the large platelet pigment particles tend to be shear sensitive and break easily during incorporation into a high-molecular-weight substrate, such as molded plastics, fibers and even automotive paint systems. Thus, the large particle size, platelet copper phthalocyanine pigments have the disadvantage that their opacity, color shade and effect are variable, depending on the incorporation time, method and equipment.
The present invention relates to a beta copper phthalocyanine pigment having unique and surprising color characteristics. In particular, the inventive pigment is characterized by its masstone and tint reflection spectra from 400 to 700 nm. The inventive pigment is also useful as a stir-in pigment, but more shear resistant than large particle size platelet forms of copper phthalocyanine because it has an advantageous particle size, which is generally in the range from 0.1 to 9 .mu.m, and a non-platelet shape. Despite its smaller particle size and non-platelet shape, the inventive pigment shows the flop effects generally associated with large particle size, platelet-shaped pigments when incorporated into a coating composition, such as an automotive paint, yet generally yields coatings having a smoother and higher gloss surface due to its smaller particle size and non-platelet shape.